424 DESIGN OF HAUNCHED COMPOSITE CONNECTIONS FOR LONG SPAN BEAM CONSTRUCTION J Y Richard Liew, Y H Ng and N E Shanmugam Department of Civil Engineering National University of Singapore BLK E1A, 1 Engineering Drive 2, Singapore 117576 ABSTRACT One of the structural options for beam spans beyond 15m is the haunched beam. By developing continuity at the supports, beam moments and deflections are reduced and this can lead to overall economy by enabling the use of shallower and lighter beam. This paper investigates the behavior of steel-concrete composite haunch connections. Experiments are carried out to study the moment-rotation characteristics of the connections and ultimate moment capacity of the composite sections. Design implications related to composite haunched beams are discussed. INTRODUCTION The authors have developed an advanced inelastic analysis model for analyzing the behavior of three-dimensional semi-continuous frames [Liew et al., (1 )]. The analysis and design methodology has been verified against test results involving full-scale testing of frames and connections [Liew et al., (2 )]. Recent work has been focused mainly on composite frames and their connections [Liew et al., (3 )]. Experimental work is currently on going to verify the capability of the analysis model for analyzing building framing systems including the effects of composite beams and connections [Liew et al. (1) , (3) & (4) ]. In recent times, the demand for long-span and column-free space in buildings has necessitated further research into the behavior of haunched beams since they are considered to be an efficient and economical form for long span construction. Haunched beams are designed by assuming a rigid moment connection between the beams and columns [Lawson and Rackham, (5 )]. Depth and length of a haunch may be chosen to enable an economical method of transferring moment into the column and in reduction of beam depth to a practical minimum. Haunched composite beams in which steel beams are designed to act in conjunction with concrete slab of definite width could result in shallow beams, provide a long unobstructed space for services and increase in speed of construction. Past work on haunched beams focused mainly on steel haunched connections under negative moment. Design methods have been proposed for continuous composite beams, but the hogging beam section and connections are designed as non-composite [Lawson and Rackham, (5 ); Boswell, (6 )]. The object of this paper is to report on the experimental results obtained from sub- assembly tests of composite haunch beams. The experimental program is presented and the results for ultimate moment capacity of the tested haunched connections are given. A design